1 Introduction

From within a Virtual Service, one or more â€˜Sub-Virtual Servicesâ€™ (SubVSs) can be created. SubVSs are useful when there are complex applications that require a larger number of Virtual Services. SubVSs may be used for certain configurations such as Exchange or Lync.

1.1 Document Purpose

This document describes how to add and configure SubVSs on the KEMP LoadMaster using the LoadMaster Web User Interface (WUI).

1.2 Intended Audience

This document is intended to help anyone who wishes to learn about or implement SubVSs on their LoadMaster configuration.

2 Advantages of SubVSs

Using SubVSs has many advantages, such as:

SubVSs are linked to, and use the IP address of, the â€˜parentâ€™ Virtual Service.

Using SubVSs reduces the number of IP addresses required by applications such as Lync or Exchange

SubVSs do not require non-transparency

SubVSs may have different settings (such as content rules) to the parent Virtual Service and to each other

Using a SubVS provides the ability to have content switching and persistency on the same Virtual Service

Using a SubVS gives the ability to perform multiple health checks on the same Virtual Service

3 Prerequisites

There are a few prerequisites/points to note before setting up a SubVS:

Real Servers and SubVSs cannot be associated with the same Virtual Service. A SubVS can only be added to a Virtual Service if there are no Real Servers set up on it already. A real server can be associated with a SubVS if required.

4.1 Add a SubVS

1. Expand the Real Servers section (if there are already SubVSs on this Virtual Service this section will be called SubVSs).

2. Click the Add SubVSâ€¦ button (or Add New â€¦ button if this is not the first SubVS to be added to this Virtual Service).

3. A success message will appear, as illustrated in the above screenshot. Click the OK button.

When the first SubVS is added to a Virtual Service the Real Servers section will be replaced with the SubVSs section in the Virtual Services configuration page. Any SubVSs of the relevant Virtual Service will be listed in this section.

When a SubVS is added to a Virtual Service, the Transparency setting on the Virtual Service is enabled and cannot be changed. This is because the Virtual Service forwards the client request transparently to the SubVS. The Transparency setting on the SubVS can be enabled or disabled as required.

The SSL Acceleration and Reencrypt options must be set in the parent Virtual Service, not in the SubVS. If these options are enabled, data is decrypted, then passed to the SubVS and re-encrypted on the way out of the SubVS.

For Exchange, KEMP recommends that ESP is not enabled on the parent service but instead is enabled in the SubVSs.

When using SNMP monitoring of ESP-enabled Virtual Services that were created using a template, ensure to monitor each SubVS directly rather than relying on the master service. This is because the Authentication Proxy sub-service will always be marked as up and, as a consequence, so will the master service.

SubVS Name: An identifiable name for the SubVS. This field is optional but KEMP recommend that SubVSs are named as it may get confusing if several SubVSs exist.

In addition to the usual alphanumeric characters, the following â€˜specialâ€™ characters can be used as part of the Service Name: . @ - _ However, there must be at least one alphanumeric character before the special characters.

SubVS Type: Setting this controls the options displayed for the SubVS. Itâ€™s important to make sure the SubVS Type is set according to the type of application is being load balanced.

SubVS Weight: This will be used when determining the priority of the SubVS.

SubVS Limit: This is the maximum number of connections that can be forwarded to this SubVS before it is taken out of rotation from the main Virtual Service. The maximum limit is 100,000.